Sonic Advance 2
Game Boy Advance
Access True Area 53:
To unlock 'true area 53' (the hidden zone), beat the game with all the emeralds
for every character.You'll warp into space as Super Sonic for the final fight
Play as Cream:
Beat the Leaf Forest level as Sonic.
Play as Tails:
Beat the Music Plant level as Sonic.
Play as Knuckles:
Beat the Sky Canyon level as Sonic.
Play as Amy:
Beat the game with all seven Chaos Emeralds as Cream, Knuckles, Sonic, and Tails.
Thanks to Revolution reader jonathan mcgregor!